Fingerprint sensors comprising electrodes for measuring characteristics in a finger surface are well known. For example, U.S. Pat. No. 7,110,577, U.S. Pat. No. 5,963,679, U.S. Pat. No. 6,069,970, U.S. Pat. No. 8,866,347 and Ser. No. 14/582,359 describe sensors based on different impedance or capacitance measurement principles with strip-shaped or matrix sensors comprising a number of individual sensor elements.
Fingerprint sensors are found in all kind of devices such as PC's, tablets, smart phones and smart cards for the security and ease of use it provides. The widespread use of fingerprint sensors may also provide a security problem as fingerprint sensors have been spoofed by spoof fingerprints produced from latent fingerprints. Current art fingerprint sensors typically attempt to mitigate this problem with additional security measures, such as live finger detection, at the cost of increased false rejection of fingerprints and reduced ease of use. There is, therefore, a need in the industry for an improved fingerprint sensor that is specifically architected to improve the anti-spoof protection without degrading the ease of use of the fingerprint sensor.